When supporting a trainee pharmacist on OTC cough suppressants, which of the following medications is available over-the-counter as a cough suppressant?

• A. Diphenhydramine
• B. Guaifenesin
• C. Codeine
• D. Dextromethorphan

Answer: (D)

Dextromethorphan is the OTC cough suppressant here. It works as a central antitussive, meaning it acts on the cough center in the brain to dampen the urge to cough, and it’s sold over the counter in many regions either alone or in combination cold medicines. That makes it the standard choice for OTC cough suppression.

Guaifenesin, by contrast, is an expectorant. It helps loosen and thin mucus so it can be cleared more easily, but it doesn’t directly suppress the cough reflex.

Diphenhydramine is an antihistamine with some antitussive effects, but it’s primarily used for allergy symptoms and its sedating properties; it’s not the typical go-to OTC cough suppressant.

Codeine is an opioid with antitussive effects, but it’s a controlled substance in many places and not available OTC, which is why it isn’t the OTC choice here.

So, the best option for an OTC cough suppressant is dextromethorphan.